linux-kernel - Re: [PATCH v3 1/1] ovl: setxattr: don't deadlock when called from ima_fix

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 30 May 2016 17:50:07 +0100
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	Krisztian Litkey <kli@....fi>,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	linux-unionfs@...r.kernel.org,
	Krisztian Litkey <krisztian.litkey@...el.com>,
	linux-security-module <linux-security-module@...r.kernel.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/1] ovl: setxattr: don't deadlock when called from
 ima_fix_xattr.

	Only tangentially related, but... that bug had been discussed,
without any results: the fallback in ima_d_path() to ->d_name.name is
completely broken.  There is no warranty whatsoever that dentry won't be
renamed, with its earlier (too long to be embedded into dentry itself)
->d_name.name getting freed.  Right under your code.

	Could we please get rid of that thing?  "A message in a near-oom
situation might be less informative than we'd like" is better than
"this code might end up dereferencing freed memory".

	Another similar bug is in ima_collect_measurement() -
        const char *filename = file->f_path.dentry->d_name.name;
	...
                integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
                                    filename, "collect_data", audit_cause,
with no warranty whatsoever that you are not passing a pointer to freed
memory.  The same goes for ima_eventname_init_common() -
        if (event_data->file) {
                cur_filename = event_data->file->f_path.dentry->d_name.name;
                cur_filename_len = strlen(cur_filename);
        } else  
...
        return ima_write_template_field_data(cur_filename, cur_filename_len,
                                             DATA_FMT_STRING, field_data);